1. Field of the Invention
The invention is directed to a blade bearing or nacelle bearing of a wind turbine, the bearing comprising two planar rings mounted adjacent to each other, and rotatable relative to each another, for connection on one side to a hub of the wind turbine and on the other side to a blade of the wind turbine, or for connection on one side to the tower of the wind turbine and on the other side to the gondola of the wind turbine.
2. Description of the Prior Art
Wind turbines place extreme demands on the materials and assemblies used. Because of the height of the structure, on the one hand, the materials and assemblies—especially in the region of the wind wheel and the gondola—must be as light as possible, since they have to be supported by the tower; but at the same time, these elements are subjected to extreme forces—including wind pressure and gusts—and therefore must be extremely robust. Particular complications result, especially in the region of the blade and nacelle bearings, since these components naturally have large diameters and, for reasons of weight, relatively small cross sections compared to the diameter; hence, there is always potential for deformation, especially if the structural elements connected to them become deformed. This, in turn, leads to serious internal stresses and consequently to increased wear and a greatly reduced service life for the affected bearing. Especially with radial bearings, which are the type most commonly used as blade or nacelle bearings, radial deformation of a ring, in which its ideal circular shape is bent elliptically, for example, is highly detrimental, since not only can individual rolling elements of the rolling bearing be overloaded in this way, but the seal covering the gap can also lose tightness in places, resulting in the leakage of lubricant or even the ingress of moisture or foreign bodies. At the same time, the active pivoting of this bearing—to adjust the pitch of the blades or the orientation of the gondola—places heightened demands on the mechanical systems used for this purpose, since considerable inertial forces must be overcome due to the high masses involved. Large servomotors, in turn, mean high weights and should therefore be avoided.